This invention relates to a portable aerosol medication delivery apparatus and system for administering a desired respirable dosage of a medication in aerosol form to a patient""s lungs by oral inhalation.
The use of aerosol medication delivery systems to administer medication in aerosol form to a patient""s lungs by inhalation is well known in the art.
Conventional aerosol medication delivery systems include pressurized metered-dose inhalers (pMDIs). Conventional pMDIs typically have two components: a canister component in which the medication particles are stored under pressure in a suspension or solution form and a receptacle component used to hold and actuate the canister. The canister component typically includes a valved outlet from which the contents of the canister can be discharged. Aerosol medication is dispensed from the pMDI by applying a force on the canister component to push it into the receptacle component thereby opening the valved outlet and causing the medication particles to be conveyed from the valved outlet through the receptacle component and discharged from an outlet of the receptacle component. Upon discharge from the canister, the medication particles are xe2x80x9catomizedxe2x80x9d forming an aerosol. It is intended that the patient coordinate the discharge of aerosolized medication with his or her inhalation so that the medication particles are entrained in the patient""s inspiratory flow and conveyed to the lungs. Typically, pMDIs have used propellants, such as chlorofluorocarbons (CFCs), to pressurize the contents of the canister and to propel the medication particles out of the outlet of the receptacle component
Although conventional pMDIs have been widely used to provide many patients with the benefits of aerosol medication, conventional pMDIs have certain drawbacks. For example, an objective of aerosol therapy has been the optimization of the mass percentage of the respirable dose of an aerosol medication in order to optimize deposition in a patient""s lungs to achieve a full therapeutic effect with the least possible side-effects. Conventional pMDIs may not have always been able to meet this objective.
One drawback associated with conventional pMDIs relates to the discharge velocity of the aerosol particles. Medication particles are stored under considerable pressure in the pMDI canister and as a consequence, their velocity may be high upon discharge.
Among other things, the effect of high velocity contributes to a significant number of aerosol medication particles impacting and depositing in the patient""s oropharynx and upper airway rather than continuing their pathway through the upper airway and into the lungs. Such impaction and deposition may result in a significant portion of the medication dose being systemically absorbed or ingested. As documented in the literature [J. L. Rau, xe2x80x9cRespiratory Care Pharmacologyxe2x80x9d, 4th ed. (1994, Mosby) at pp. 256-261; K. Meeran, A. Hattersley, J. Burrin, R. Shiner, K. Ibbertson K., xe2x80x9cOral and Inhaled Corticosteroids Reduce Bone Formation as Shown by Plasma Osteocalcin Levelsxe2x80x9d, Am. J. Respir. Crit. Care Med 151:333-336], systemic absorption or ingestion of aerosol medication may cause a patient adverse side-effects, particularly when the aerosol medication is a corticosteroid. Some of these adverse side-effects include pharyngeal candidiasis, hoarseness, and adrenal suppression.
The high velocity of the aerosol medication particles may also accentuate the difficulty of a significant number of patients, particularly the very young and elderly, to coordinate actuation of the pMDI with inhalation of the aerosol medication particles generated. Failure to coordinate the actuation and inhalation maneuvers and failure to inhale slowly, have been documented by the literature [S. P. Newman, xe2x80x9cAerosol Deposition Considerations in Inhalation Therapyxe2x80x9d Chest/88/2/August, 1985/Supplement] as contributing to a significant reduction in the number of aerosol medication particles inspired and deposited in a patient""s lungs.
Impaction and deposition of aerosol medication particles on a patient""s oropharynx and upper airway may also contribute to an unpleasant taste in a patient""s mouth, particularly with certain medication solution or suspension formulations such as flunisolide.
In addition to high particle velocity, a significant number of large non-respirable medication particles may be produced upon discharge as a result of the medication suspension or solution formulation as well as the atomization process. As mentioned above, conventional pMDIs have used CFCs to propel the medication out of the pMDI actuator outlet. In view of environmental concerns with CFCs, there has been a growing interest in using non-CFC propellants, such as hydrofluoroalkanes (HFAs).
Accordingly, it is an object of the invention to provide for the delivery of respirable medication particles from a pMDI canister with a device that overcomes the disadvantages of the prior art.
It is another object to provide a device which reduces the need for a patient to coordinate activation of a pMDI canister with inhalation.
It is a further object to provide a device that reduces the delivery of non-respirable medication particles from a pMDI canister to a patient.
It is yet another object to provide a device that reduces the impaction of medication particles on a patient""s oropharynx and upper airway.
It is still another object to provide a device for the delivery of aerosol medication from a pMDI canister that uses an HFA propellant instead of a CFC propellant.
In order to address the above noted objectives, as well as other objectives, the present invention provides an improved aerosol medication delivery apparatus. The aerosol medication delivery apparatus includes a canister-holding portion and a chamber housing. The canister-holding portion has a receptacle for receipt of a pMDI canister containing a medication and a propellant. The canister-holding portion has a discharge orifice communicating with the receptacle to direct an aerosol into an interior of the chamber housing at an input end thereof. The chamber housing also has an output end from which medication can be withdrawn by inhalation by a patient. The canister-holding portion and the chamber housing are coupled together by a mechanism that provides for the canister-holding portion to be retracted into the chamber housing for storage. The coupling mechanism also allows the canister-holding portion to be extracted from its storage position in the chamber housing and pivoted into position for use when dispensing medication. According to one aspect of the present invention, the aerosol delivery system includes a containment baffle located at the output end of the chamber housing to partially block the output end.
According to another aspect, the canister-holding portion and the chamber housing are coupled together by a mechanism that provides for the canister-holding portion to be retracted into the chamber housing for storage. The coupling mechanism also allows the canister-holding portion to be extracted from its storage position in the chamber housing and pivoted into position for use when dispensing medication.
In another aspect, an aerosol medication delivery apparatus includes a chamber housing with an input end an output end. The input end receives the discharge of a medication from a pMDI canister and the output end includes a containment baffle that partially blocks the output end. The pMDI canister is received in an elastomeric backpiece that is adapted to accommodate various sizes of actuator boot mouthpieces.